linux-kernel - Re: [RFC 03/12] bio: add bio_set

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Message-ID: <aUERE4HJN_ek4Eba@infradead.org>
Date: Mon, 15 Dec 2025 23:58:11 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Andreas Gruenbacher <agruenba@...hat.com>
Cc: Christoph Hellwig <hch@...radead.org>, Jens Axboe <axboe@...nel.dk>,
	Chris Mason <clm@...com>, David Sterba <dsterba@...e.com>,
	linux-block@...r.kernel.org, linux-btrfs@...r.kernel.org,
	linux-raid@...r.kernel.org, dm-devel@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC 03/12] bio: add bio_set_errno

On Mon, Dec 08, 2025 at 12:10:10PM +0000, Andreas Gruenbacher wrote:
> Add a bio_set_errno(bio, errno) helper that sets bio->bi_status to
> errno_to_blk_status(errno) if errno != 0.  Replace instances of this
> pattern in the code with a call to the new helper.
> 
> The WRITE_ONCE() in bio_set_errno() ensures that the compiler won't
> reorder things in a weird way, but it isn't needed to prevent tearing
> because a single-byte field like bi_status cannot tear.

Not a fan of this.  We should not be doing that very often (and as
seen by the diff don't), so don't add a helper for it that makes
people do it more often.